1. Technical Field
The invention relates to a lens driving system, and more particularly, to a lens driving system that is mounted on a lens device having a variable power lens moving mechanism for moving a variable power lens group and/or a focus lens moving mechanism for moving a focus lens group and a driving section to which operation power is supplied from a camera device.
2. Description of the Related Art
Recently, in banking branches or retail stores, monitoring cameras constituted by CCDs and the like are often used. In this type of the monitoring cameras, a varifocal lens of which angle of view and focus are manually adjustable is used as an alternative of a fixed focus lens or a zoom lens.
When the fixed focus lens is used, focus adjustment can be made but the angle of view cannot be adjusted. Therefore it is required to prepare a plurality of lens and select a lens that provides a desired photographing condition, from among the plurality of lens. When the zoom lens is used, the angle of view can be adjusted and its focus does not change even if the angle of view is adjusted. Therefore, when the focus is adjusted once during the installation, a desired photographing condition can be easily achieved by adjusting the angle of view only. On the other hand, when the varifocal lens is used, the angle of view can be adjusted. However, the varifocal lens does not have the configuration that the focus does not change even if the angle of view is adjusted. Therefore, it is required to readjust its focus again each time the angle of view is adjusted during the installation. However, since the configuration of the varifocal lens is less complex than that of the zoom lens, the manufacturing cost can be relatively reduced. Thus, the varifocal lens is often used for the purpose of monitoring cameras.
The monitoring cameras are installed on ceils, wall faces, or the like of the stores, the optical axes of the lenses are set in a certain direction, and then, the angles of field and focuses are appropriately adjusted, for completing the installation of the monitoring cameras. Here, generally, the angle of view and the focus of the varifocal lens have been adjusted by adjusting a manual adjustment section provided in a lens main body. However, recently, an electrical adjustment based on a remote operation is demanded for the following reasons.
Generally, the focus of the varifocal lens is adjusted by temporarily connecting a monitor to the camera and checking an image displayed on the monitor. Thus, it is difficult to manually adjust the focus while checking the monitor, particularly, in the case where the camera is installed to a high location. In addition, since a delicate adjustment is required as resolution of the camera increases, there is the case where it is difficult to manually adjust the focus. In addition, when a dome-type monitoring camera is used, a dome is installed after the angle of view and focus are adjusted. However, a light path length may change due to installment of the dome. As a result, the adjusted focus is misaligned. In such a case, it becomes necessary to repeat manual adjustment of the focus and attachment/detachment of the dome in a trial-and-error manner. Accordingly, it may be difficult to install the monitoring camera.
Accordingly, JP 2001-21785 A discloses an electrically driven varifocal lens that enables an operation switch to adjust its angle of view and focus and automatically adjusts a photographing condition by setting predetermined adjustment condition in advance.
A varifocal lens requires that its focus is adjusted each time every time its angle of view is adjusted. However, this adjustment is required only at a time of installation. An expensive system that has a zoom lens only for the purpose of the adjustment is less-needed. Thus, if an electrical adjustment based on a remote operation using an infrared ray, a weak electric wave, or the like is applied to a varifocal lens, an inexpensive system can be built although the efficiency of an adjustment operation is lower than that of the zoom lens.
However, generally, operation power supplied from a camera is supplied for the purpose of driving an iris, an infrared ray cut-off filter, and the like and is not supplied for the purpose of controlling driving the angle of view and focus. Thus, when electrical adjustment based on a remote operation is applied, there is a need for a dedicated camera, instead of a general camera, that enables the angle of view and focus to be driven and controlled driven to be controlled. However, if the dedicated camera is used, versatility of system integration is reduced and the effect of reduction in the manufacturing cost achieved by using the varifocal lens becomes meaningless.